Acrylic Acid-acrylate Copolymer Thickening Agents - Patent 4268641

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United States Patent: 4268641


































 
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	United States Patent 
	4,268,641



 Koenig
,   et al.

 
May 19, 1981




 Acrylic acid-acrylate copolymer thickening agents



Abstract

Copolymers of acrylic acid and nonionic surfactant acrylates have been
     found to be useful thickening agents for both aqueous solutions and
     water/liquid hydrocarbon emulsions.


 
Inventors: 
 Koenig; Harvey S. (Charlotte, NC), Bryant; George M. (Charleston, WV) 
 Assignee:


Union Carbide Corporation
 (New York, 
NY)





Appl. No.:
                    
 06/154,521
  
Filed:
                      
  May 29, 1980

 Related U.S. Patent Documents   
 

Application NumberFiling DatePatent NumberIssue Date
 32771Apr., 1979
 

 



  
Current U.S. Class:
  525/367  ; 524/558; 524/833; 525/369; 525/374; 525/378; 525/379; 526/310; 526/311; 526/318.41; 526/328; 526/932
  
Current International Class: 
  C08F 8/44&nbsp(20060101); C08F 8/00&nbsp(20060101); C08F 020/06&nbsp(); C08F 020/26&nbsp(); C08F 020/36&nbsp()
  
Field of Search: 
  
  













 526/317,328,310,311,910 260/29.6RW,29.6PM,29.6CM,29.6AT 525/367,369,374,378,379
  

References Cited  [Referenced By]
U.S. Patent Documents
 
 
 
2892793
June 1959
Stewart et al.

3035004
May 1962
Glavis

3052648
September 1962
Bauer

3106482
October 1963
Van Dijk

3317483
May 1967
Verdol

3436378
April 1969
Azorlosa et al.

3492254
January 1970
Strand et al.

3499876
March 1970
Field et al.

3652497
March 1972
Junas et al.

3657175
April 1972
Zimmerman et al.

3660339
May 1972
Schuh

3708445
January 1973
Junas et al.

3794608
February 1974
Evani et al.

3894980
July 1975
DeTommaso

3896070
July 1975
Tummler et al.

3896072
July 1975
Tummler et al.

4085167
April 1978
Lewis et al.

4138381
February 1979
Chang et al.



   Primary Examiner:  Kight, III; John


  Attorney, Agent or Firm: Crowe; Bernard Francis



Parent Case Text



This is a continuation-in-part of Ser. No. 032,771 filed Apr. 24, 1979, now
     abandoned.

Claims  

What is claimed is:

1.  A normally solid, base-neutralized copolymer having copolymerized therein about 90 to about 99 mole percent of a carboxyl-containing, ethylenically unsaturated hydrocarbon
and about 1 to about 10 mole percent of a nonionic surfactant acrylate having the formula: ##STR3## wherein R is hydrogen or methyl, R' is a hydrophobe selected from the group consisting of alkyl--O--, alkyl--NH--, and alkyl--CO--, where the alkyl
contains 4 to about 30 carbon atoms, A is a divalent radical selected from the group consisting of oxyethylene units or mixed oxyalkylene units having the general formula:


wherein n is an integer having values from 2 to 4 and x is an integer having values of about 5 to about 40, said surfactant acrylate having an HLB value of about 10 to about 19.


2.  Copolymer claimed in claim 1 wherein R is hydrogen.


3.  Copolymer claimed in claim 1 wherein R' is alkyl--O--.


4.  Copolymer claimed in claim 1 wherein A is oxyethylene.


5.  Copolymer claimed in claim 1 wherein A is mixed oxyalkylene groups.


6.  Copolymer claimed in claim 1 wherein x is 8 to 12.


7.  A normally solid, base-neutralized copolymer having copolymerized therein about 90 to about 99 mole percent of a carboxyl-containing, ethylenically unsaturated hydrocarbon and about 1 to about 10 mole percent of a nonionic surfactant acrylate
having the formula: ##STR4## wherein R is hydrogen or methyl, R' is a hydrophobe selected from the group consisting of alkyl--NH-- and alkyl--CO--, where the alkyl contains 4 to about 30 carbon atoms, A is a divalent radical selected from the group
consisting of oxyethylene units or mixed oxyalkylene units having the general formula:


wherein n is an integer having values from 2 to 4 and x is an integer having values of about 5 to about 40, said surfactant acrylate having an HLB value of about 10 to about 19.  Description 


BACKGROUND OF THE INVENTION


This invention pertains to the preparation of copolymers of acrylic acid and nonionic surfactant acrylates and more particularly to their use as thickening agents for aqueous solutions and water/liquid hydrocarbon emulsions.


Various synthetic thickening agents composed of carboxylic acid monomers, such as acrylic acid, and a polyfunctional crosslinking monomer are known in the art.  These interpolymers produce viscous, aqueous mucilages.  However, these interpolymers
rely upon the crosslinking monomer to achieve the desired aqueous thickening properties.  U.S.  Pat.  Nos.  2,798,053, 2,858,281, and 3,426,004 disclose respectively polyallyl sucrose, polybutadiene and triallyl phosphate or phosphite esters as
crosslinking monomers for polyacrylic acid to achieve interpolymers capable of producing viscous aqueous mucilages upon neutralization.  U.S.  Pat.  No. 2,798,053 describes crosslinked copolymers of acrylic or methacrylic acid with minor amounts of
vinyl, allyl and methallyl ethers of polyhydric alcohols having at least 4 carbon atoms and at least 3 alcoholic hydroxy groups, wherein the preferred polyalkenyl polyether monomers are polyallyl sucrose and polyallyl pentaerythritol containing an
average of at least about 3 allyl groups per polyhydric alcohol.  Similarly U.S.  Pat.  No. 3,426,004 describes crosslinked interpolymers of acrylic or methacrylic acids with from 0.1 to 2 weight percent of a polyallyl phosphate or a polyallyl phosphite
ester such that at least 2 allyl ester functionalities and preferably 3 allyl ester functionalities are incorporated into the phosphate or phosphite monomer.  U.S.  Pat.  No. 2,858,281 discloses the use of a polymeric crosslinking agent, polybutadiene,
in forming the acrylic acid interpolymers.


U.S.  Pat.  No. 3,530,102 issued to Union Carbide Corporation describes terpolymers of maleic anhydride, vinyl alkyl ether and divinylbenzene as thickening agents.


U.S.  Ser.  No. 494,447 discloses ethylene-maleic anhydride interpolymers crosslinked with triallyl isocyanate to form a thickening agent.


U.S.  Pat.  Nos.  3,915,921 and 3,940,351 disclose synthetic thickening agents composed of acrylic acid and non-crosslinking comonomers.  Alkyl acrylate esters having 10 to 30 carbon atoms in the alkyl portion are described as the
non-crosslinking comonomers.  Optionally a crosslinking agent is also disclosed, polyalkenyl polyethers.


The use of nonionic surfactant monomers and the preparation of synthetic thickening agents has been disclosed in U.S.  Pat.  Nos.  3,779,970 and 3,794,608.


Belgium Pat.  No. 846,348 describes synthetic thickening agents composed of carboxamides and esters of maleic or fumaric acids which are useful as pigment printing thickeners.  The maleic or fumaric acid is esterified with nonionic surfactants,
such as, polyalkylene oxide adducts of alkyl alcohols, arylalkyl alcohols, and the like.


Polymers composed of a carboxylic acid monomer and one or more comonomers of which one monomer may be a multifunctional crosslinking monomer and in which the majority of the polymer is derived from the hydrophilic carboxylic acid monomer are
typical of the synthetic thickening agents known in the art.  Neutralization of the carboxylic acid-containing polymers in water produces gel-like polymers or mucilages exhibiting high viscosities.  These polyelectrolyte polymers are useful as bodying
and suspending agents in various applications such as pharmaceuticals, dentifrices, ointments, coatings, printing pastes, and the like.  The rheological and solution properties of the neutralized polymers impart desirable characteristics to the various
mucilage formulations.  For example, the carboxylic acid-containing interpolymers described in several of the references delineated above produce highly viscous aqueous solutions which are thixotropic in nature and are readily formulated into useful
creams, ointments, pastes, and the like.  However, these high molecular weight interpolymers suffer the disadvantage of being sensitive to inorganic electrolytes, such as, sodium chloride.  The ion-sensitive thickeners do not effectively maintain their
viscosity and drastic viscosity losses in the presence of inorganic electrolytes are observed.  Such ion-sensitivity is deleterious to the performance of these thickeners when they are included in formulations such as latexes, food preparations, cosmetic
creams, ionic detergents, and dye pastes.  One attempt to overcome this deficiency was disclosed in U.S.  Pat.  Nos.  3,915,921 and 3,940,351 wherein polymers composed of acrylic acid and long-chain alkyl acrylates were described as being less
electrolyte sensitive than other carboxylic acid interpolymers of the prior art.  However these synthetic thickeners are less efficient thickeners than the interpolymers and require the addition of a crosslinking monomer to attain high solution
viscosities.  Incorporation of the crosslinking agent reduces the electrolyte compatability far below the compatabilities of polymers without the crosslinker.


Polymers composed of carboxylic acid monomers and crosslinking monomers are used as thickeners for water-hydrocarbon emulsions.  Water-hydrocarbon emulsions used in the preparation of printing inks, pigment printing pastes, and the like include
synthetic thickeners which serve to increase the paste viscosity and to impart thixotropic properties to the formulation.  Prior art polymers function adequately but the water-hydrocarbon emulsion viscosities are less than the viscosities obtained in
water solutions.  This requires the addition of more thickener to the paste to obtain the viscosities exhibited in an all aqueous system.  Thickeners which maintain or exhibit an increase in the water-liquid hydrocarbon emulsion viscosity compared to the
aqueous viscosity would permit the formulator greater latitude in the preparation of printing inks and pastes.  In addition, the use of less thickener imparts a more thixotropic rheology to the formulation, a property required for the proper application
of the printing ink or paste to the medium being printed.


It is therefore an object of this invention to provide thickening agents with improved salt tolerance.


It is another object of this invention to provide thickening agents which have a high thickening efficiency in aqueous solutions.


It is still a further object of this invention to provide thickening agents which have a high thickening efficiency in water-liquid hydrocarbon emulsions.


SUMMARY OF THE INVENTION


The above objects are provided by a normally solid, base-neutralized copolymer having copolymerized therein about 90 to about 99 mole percent of a carboxyl-containing ethylenically unsaturated hydrocarbon and about 1 to about 10 mole percent of a
nonionic surfactant acrylate having the formula: ##STR1## where R is hydrogen or methyl, R' is a hydrophobe which can be alkyl--O--, alkyl--NH--, or alkyl--CO--, where the alkyl contains r to about 30 carbon atoms, A is a divalent radical selected from
the group consisting of oxyethylene units or mixed oxyalkylene units having the general formula --OC.sub.n H.sub.2n -- wherein n is an integer having values from 2 to 4 and x is an integer having values of about 5 to about 40, said surfactant acrylate
having an HLB value of about 10 to about 19.


The preferred carboxyl-containing ethylenically unsaturated hydrocarbon is acrylic acid.  One may also use methacrylic acid, maleic acid, fumaric acid, itaconic acid, and the like, if desired.


Although about 90 to about 99 mole percent of carboxyl-containing ethylenically unsaturated hydrocarbon can be present in the copolymer of this invention, it is preferred to incorporate about 96 to about 99 mole percent in the copolymer.


The nonionic surfactant acrylate used to make the copolymer of this invention can be prepared by known methods of acrylation with acrylic acid of an hydroxyl terminated compound consisting of a hydrophobe and hydrophile moiety.  This hydroxyl
terminated compound is prepared by forming an alkylene oxide adduct of a fatty acid, a primary or secondary saturated aliphatic alcohol or a saturated aliphatic amine.  The hydrophobe moiety obtained thereby contains about 4 to 30 carbon atoms,
preferably about 11 to 30 carbon atoms and even more preferably about 15 to 30 carbon atoms.  The hydrophile moiety can contain at least 5 oxyethylene units when the alkylene oxide used is ethylene oxide and preferably at least 7 moles of oxyethylene
units or in the case of an alkylene oxide mixture of ethylene oxide and propylene oxide, at least 7 mixed oxyalkylene units and preferably at least 9 mixed oxyalkylene units.


The acylation can be effected by such well known reactions as the Schotten-Baumann method, and the like.  The resultant non-ionic surfactant acrylates thus obtained should have a HLB value of about 10 to 19 and preferably about 12 to 18.  The HLB
or hydrophilic-lipophilic balance method of surfactant classification defines amphipathic materials, i.e., those having hydrophilic and lipophilic groups in their structures corresponding to numerical values assigned according to the solubility of the
surfactant in oil or water.  The HLB values can also be calculated from group contributions.  The HLB scheme is described in detail in "Emulsions and Emulsion Technology," Surfactant Science Series, Vol. 6, Part I, page 77, edited by K. J. Lissant,
Marcel Dekker, Inc., New York City, 1974.


The preparation of non-ionic surfactants is described in Nonionic Surfactants, Vol. 1, editor M. J. Schick, Marcel Dekker, Inc., New York City, 1967.  The preparation of acrylate esters of nonionic surfactants is also well known in the art and
general preparations are disclosed in U.S.  Pat.  Nos.  3,341,627 and 3,896,161.


In the case of mixed alkylene oxide adducts the copolymers of this invention can be prepared with blocks of ethoxy units followed by propoxy units, propoxy units followed by ethoxy units or a random mixture of both.


The copolymers of this invention are preferably made by polymerizing the comonomers in an inert diluent having solubilizing character on the monomer ingredients but substantially none on the resultant copolymer.  Suitable diluents include
aromatic solvents such as benzene, toluene, xylene, tetralin, and the like, as well as saturated aliphatic solvents including hexane, heptane, octane, and the like, and saturated cycloaliphatic compounds, such as cyclopentane, cyclohexane, cycloheptane,
and the like.  Halogenated solvents can also be used, such as, carbon tetrachloride, bromotrichloromethane, trichlorofluoromethane, tetrafluoromethane, 1,1,2-trichloro-1,2,2-trifluoromethane, 1,2-difluoro-1,1,2,2-tetrachloroethane, trichloroethane,
perchloroethylene, and the like.


Polymerization of the monomers in the diluent is carried out in the presence of a solvent-soluble free radical catalyst in an inert atmosphere in a closed vessel.  The temperature of polymerization may be varied from room temperature to about
150.degree.  C. depending upon the diluent and free radical catalyst employed.  Polymerization of comonomers in an open vessel under reflux and under an inert atmosphere is also suitable.  The temperature of polymerization under these conditions depends
upon the boiling point of the inert diluent used.  The polymerizations proceed to yield 90 to 100 percent copolymer upon reaction at 60.degree.  to 110.degree.  for 6 hours or longer.


Suitable solvent-soluble free radical catalyst include benzoyl peroxide, hydrogen peroxide, caprylyl peroxide, cumene hydroperoxide, tertiary butyl perbenzoate, azobisisobutyronitrile, and the like.


Inasmuch as the copolymers thus prepared in the diluent enumerated above which are solvents for the comonomers and non-solvents for the copolymers the product precipitates from the reaction mixture as a fine powder.  Removal of the diluent by
filtration and decantation or vacuum stripping yields a fine, white, powdery copolymer.


Alternative methods of polymerization including inert emulsion polymerization in hydrocarbon solvents and emulsion polymerization in aqueous salt solution can be used but are more difficult to control and some cases require a monomer feed
sequence reaction as opposed to simple monomer batch charge.


The copolymers of this invention attain their maximum use as synthetic thickeners in aqueous or water-hydrocarbon solvent emulsions upon neutralization of the copolymers prepared as above with a base.  The term base as used herein includes both
organic and inorganic bases exemplified by ammonium hydroxide, sodium hydroxide, alkyl amines, alkali carbonates, alkali bicarbonates, ammonium or amine salts of hydroxide, and the like.  The choice of base then is not narrowly critical and a wide
latitude in chosing one may be used by those skilled in the art.


Optimum aqueous thickening is obtained with copolymers composed of acrylic acid and from about 1 to about 4 mole percent of a nonionic surfactant acrylate having an HLB of about 18.  The hydrophile portion of the surfactant thus described
contains about 20 to about 40 moles and preferably about 30 to 40 moles of ethylene-oxide.  The hydrophobe portion of the surfactant acrylate in the above example is composed of a monohydric hydrocarbon alcohol, acid or amine having at least 11 carbon
atoms and preferably at least 15 carbon atoms contained therein.  The chemical nature of the hydrophobe, that is, primary or secondary alcohol or amine or fatty acid, exerts less influence on the copolymer's aqueous thickening efficiency than its
molecular weight, i.e., total number of carbon atoms in the copolymer.


Optimum water-hydrocarbon solvent emulsion viscosities are obtained by polymers composed of acrylic acid and from about 1 to about 4 mole percent of nonionic surfactant acrylate such that the hydrophobe of the surfactant is composed of a linear
primary alcohol of at least 8 carbon atoms and preferably at least 11 carbon atoms and the hydrophile portion is composed of at least 7 moles of ethylene oxide or mixed ethylene oxide-propylene oxide, and preferably at least 9 moles of alkylene oxide.


Polymers of this invention displaying optimum salt compatability compared to synthetic thickeners of the prior art are composed of acrylic acid in about 1 to about 4 mole percent of a nonionic surfactant acrylate such that the hydrophobe portion
of the surfactant acrylate is composed of a linear primary alcohol containing at least 8 carbon atoms, preferably at least 11 carbon atoms and the hydrophile portion of the surfactant is composed of at least 5 moles of ethylene oxide or mixed oxides,
preferably at least 7 moles of ethylene oxide or mixed oxides.


The effects of polymer composition on the aqueous and water-hydrocarbon emulsion viscosities and the ion sensitivity of the polymers were assessed by measuring the Brookfield (Model RVT) viscosities at 20 rpm.


The invention is further described in the examples which follow.  All parts and percentages are by weight unless otherwise specified. 

EXAMPLE 1


PREPARATION OF NONIONIC SURFACTANT ACRYLATES


The Schotten-Baumann method was used for preparing a series of nonionic surfactant acrylates as follows:


A mole equivalent of a nonionic surfactant was dissolved in five times its weight of toluene contained in a four-necked-round bottomed flask equipped with a condenser, thermometer, dropping funnel, mechanical stirrer, nitrogen inlet tube and
Glas-col heating mantle.  The nonionic surfactants used in the preparation of the surfactant acrylates included linear primary alcohol ethoxylates, linear primary alcohol ethoxylates-proproxylates, and secondary alcohol ethoxylates.  A mole equivalent of
triethylamine was added to the stirred solution.  A mole equivalent of acryloyl chloride dissolved in a equal weight of toluene was added to the solution portion wise.  The reaction was allowed to proceed at reflux temperature for 4 hours.  The reaction
mixture was then cooled to room temperature and the amine hydrochloride which formed was removed by suction filtration.  The toluene was removed from the filtrate in vacuo to yield the nonionic surfactant acrylate.  Identification of specific
commercially available surfactants together with the number of ethoxy and/or propoxy units as well as their HLB values and molecular weights are given in Table 1.


EXAMPLE 2


PREPARATION OF COPOLYMER THICKENING AGENTS


A series of batch polymerizations of acrylic acid and the acrylic acid ester of TERGITOL 15-S-40 was carried out in benzene at 60.degree.  C. using azobisisobutronitrile as the polymerization initiator.  The polymerizations were carried out in
16-ounce capped glass bottles and in an inert atmosphere of nitrogen.  The resultant polymers, insoluble in the benzene diluent, were collected by suction filtration, washed, and dried in an oven at 60.degree.  C. Aqueous solutions of the resultant
polymers were prepared by neutralizing 2.0 grams of said polymers contained in 396.5 grams of distilled water with 1.5 grams of ammonium hydroxide.  Water-Varsol (Trademark for a hydrocarbon solvent sold by Exxon Corporation having a boiling range of
315.degree.  to 380.degree.  F. and consisting mainly of saturated and aromatic distillation fractions) emulsions of the resultant copolymers were prepared by neutralizing 1.0 grams of the copolymer contained in 120.0 grams of distilled water, 75.0 grams
of Varsol, 2.5 grams of the surfactant TERGITOL 15-S-9 with 1.5 grams of ammonium hydroxide.


Table 2 delineates the viscosity data of 0.5 weight percent solutions of six acrylic acid-TERGITOL-S-40 acrylate copolymers containing 0.90 to 3.5 mole percent TERGITOL 15-S-40 acrylate copolymerized therein.  The surfactant acrylate content is
indicated as mole percent of monomer charge.  These data indicate that a maximum aqueous and emulsion viscosity is obtained at 2.0-3.0 mole percent surfactant acrylate.  The water-Varsol emulsion viscosities are considerably greater than the
corresponding aqueous viscosities.


 TABLE I  ______________________________________ Nonionic Surfactants  Surfactant EO.sup.(a)  PO.sup.(b)  HLB.sup.(c)  Mol. Wt..sup.(d)  ______________________________________ TERGITOL 15-S-40.sup.(e)  40 -- 18.0 1962  TERGITOL 15-S-12.sup.(e) 
12 -- 14.5 788  NEODOL 25-12.sup.(f)  12 -- 14.5 734  EPAL.sup.(g) 1214-7, 1  7 - 12.3 516  EPAL.sup.(h) 1214-8, 1.5  8 1.5 10.9 634  EPAL.sup.(i) 1418-6, 4.5  6 4.5 7.4 767  UCON.sup.(j) 80 HB-192  11 2 14.3 685  UCON.sup.(k) 50 HB-5100  47 35 10.0 4100 ______________________________________ .sup.(a) Moles of ethylene oxide adducted per mole of alcohol.  .sup.(b) Moles of propylene oxide adducted per mole of alcohol.  .sup.(c) Hydrophiliclipophilic balance.  .sup.(d) Weight average molecular weight. 
.sup.(e) Trademark for an ethylene oxide adduct of a mixture of C.sub.12  to C.sub.15 isomeric linear alcohols sold by Union Carbide Corp.  .sup.(f) Trademark for an ethylene oxide adduct of a mixture of C.sub.12  to C.sub.15 isomeric linear alcohols
sold by Shell.  .sup.(g) Trademark of Ethyl Corp. for a linear primary alcohol mixture  having a molecular weight of 200 and 12 to 14 carbon atoms which were  ethoxylated with 7 moles of ethylene oxide per mole of Epal 1214.  .sup.(h) Trademark of Ethyl
Corp. for a linear primary alcohol having 12  to 14 carbon atoms which were alkoxylated with 8 moles of ethylene oxide  and 1.5 moles of propylene oxide per mole of Epal 1214.  .sup.(i) Trademark of Ethyl Corp. for a linear primary alcohol having 14  to
18 atoms which were alkoxylated with 6 moles of ethylene oxide and 4.5  moles of propylene oxide per mole of Epal 1418.  .sup.(j) UCON 80 HB192 is a Trademark of Union Carbide Corp. for butanol  alkoxylated with 11 moles of ethylene oxide and 2 moles of
propylene  oxide.  .sup.(k) UCON 50 HB5100 is a Trademark of Union Carbide Corp. for butanol  alkoyxlated with 47 moles of ethylene oxide and 35 moles of propylene  oxide.


 TABLE II  ______________________________________ Aqueous and Emulsion Viscosities of  Acrylic Acid-TERGITOL 15-S-40 Acrylate Copolymers  Mole % Viscosities (cps)  TERGITOL 15-S-40 of 0.5% Polymer  Copolymer  Acrylate In Water Water-Varsol 
______________________________________ 1 0.90 7,000 39,400  2 1.35 10,400 37,200  3 2.0 22,800 80,000  4 2.5 26,000 46,000  5 3.0 21,650 72,000  6 3.5 15,600 56,000  ______________________________________


EXAMPLE 3


Employing the procedures of Example 2, a series of acrylic acid-TERGITOL 15-S-12 acrylate copolymers was made and evaluated with the results depicted in Table III.  The aqueous and water-Varsol emulsion viscosities of the polymers increase with
increasing TERGITOL 15-S-12 acrylate.  The emulsion viscosities are greater than the corresponding aqueous viscosities.


 TABLE III  ______________________________________ Aqueous and Emulsion Viscosities of  Acrylic Acid-TERGITOL 15-S-12 Acrylate Copolymers  Mole %  TERGITOL 15-S-12 Viscosities (cps) of 0.5% Polymer  Polymer  Acrylate Aqueous Water-Varsol 
______________________________________ 1 1.5 1400 22400  2 2.0 2750 45600  3 2.5 4500 56000  4 3.0 7000 70800  5 3.5 9000 81000  6 4.0 10400 78400  ______________________________________


EXAMPLE 4


Using the procedures of Example 2, a series of acrylic acid-NEODOL 25-12 acrylate copolymers was made and evaluated with the results shown in Table IV.  The aqueous and emulsion viscosities increase with increasing NEODOL 25-12 acrylate mole
percent monomer charge.  The emulsion viscosities are considerably greater than the corresponding aqueous viscosities.


 TABLE IV  ______________________________________ Aqueous and Emulsion Viscosities of  Acrylic Acid-NEODOL 25-12 Acrylate Copolymer  Mole %  NEODOL 25-12 Viscosities (cps) of 0.5% Polymer  Polymer  Acrylate Aqueous Water-Varsol 
______________________________________ 1 1.5 1276 54400  2 2.0 2175 83400  3 2.5 2990 104600  4 3.0 4085 93400  5 3.5 4240 97000  6 4.0 5340 97400  ______________________________________


EXAMPLE 5


Employing the procedure of Example 2, a series of acrylic acid-nonionic surfactant acrylates was made and evaluated.  The surfactant acrylates were EPAL 1214-7, EPAL 1214-8, 1.5 and EPAL 1418-6, 4.5.  That data depicted in Table V reveal that the
EPAL 1418-6, 4.5 surfactant acrylate containing polymers produce exceptionally viscous water-Varsol emulsions.  The other EPAL alkoxylate acrylate containing polymers produce emulsion viscosities similar to the NEODOL 25-12 acrylate containing
thickeners.  The aqueous viscosities of these polymers are less than the thickeners containing surfactant acrylates with high HLB values; that is high ethylene oxide content.


 TABLE V  __________________________________________________________________________ Aqueous and Emulsion Viscosities of  Acrylic Acid-Nonionic Surfactant Acrylate Copolymers  Mole %  Viscosities (CPS) of 0.55 Polymer  Nonionic  Containing 
Surfactant  EPAL 1214-7 EPAL 1214-8, 1.5  EPAL 1418-6, 4.5  Acrylate  Aqueous  Water-Varsol  Aqueous  Water-Varsol  Aqueous  Water-Varsol  __________________________________________________________________________ 1.5 230 16100 274 26150 2065 132600  2.0
764 44600 600 50400 3090 124400  2.5 946 61600 1460 65400 5800 125600  3.0 -- 81200 2440 79400 5600 119600  3.5 2010 9300 2710 84600 6100 121400  4.0 2065 100400 2500 99600 6600 121600 
__________________________________________________________________________


EXAMPLE 6


Using the procedure of Example 2, a series of acrylic acid-UCON Fluid acrylate copolymers was made and evaluated.  UCON Fluids 80 HB 192 and 50 HB 5100 acrylates were used to prepare the copolymers.  The data shown in Table IV reveal that the
random ethoxylate-propoxylate adducts of butanol are less efficient viscosity improvers of water-Varsol emulsions compared to the higher molecular weight linear primary alcohol hydrophobes but the aqueous viscosity efficiencies are similar.


 TABLE VI  ______________________________________ Aqueous and Emulsion Viscosities of  Acrylic Acid-UCON Fluid Acrylic Copolymers  Viscosities (CPS) of 0.5% Polymer  Mole % Containing  UCON FLUID  UCON 80 HB 192 UCON 50 HB 5100  Acrylate Aqueous
Water-Varsol  Aqueous  Water-Varsol  ______________________________________ 1.0 -- 668 3720 --  2.0 1200 2720 8760 --  3.0 3870 7650 1720 --  4.0 6320 12150 -- --  ______________________________________


EXAMPLE 7


Using the polymers described in Examples 2-6, the ion sensitivities were assessed by measuring the viscosities of aqueous solutions to which increments of sodium chloride were added.  The data in Table VII present the percent retained viscosities
of 0.5 weight percent polymer solutions containing various weight percent sodium chloride.  The polymers containing linear primary alcohol alkoxylate acrylates exhibit viscosities equal to or greater than the host solution.


 TABLE VII  ______________________________________ Salt Sensitivities of Acrylic Acid Copolymers  Containing 2.0 Mole Percent Nonionic Surfactant Acrylate  Percent Retained  Nonionic Viscosities (CPS) of 0.5% Polymer  Surfactant Solutions
Containing NaCl Conc. of:  Acrylate 0.25 0.50 1.0 2.0  ______________________________________ TERGITOL 15-S-40  5 1 -- --  TERGITOL 15-S-12  78 53 -- --  NEODOL 25-12 124 87 30 --  EPAL 1214-7 163 326 280 83  EPAL 1214-8, 1.5  170 298 225 55  EPAL
1418-6, 4.5  177 157 70 50  UCON 80 HB 192 44 31 -- --  ______________________________________


EXAMPLE VII


The following example is presented to distinguish the instant invention over the disclosure of Chang et al. in U.S.  Pat.  No. 4,138,381.  The teachings of Chang et al. comprise terpolymers consisting essentially of (a) at least one unsaturated
carboxylic acid of 3 to 6 carbon atoms, (b) at least one alkyl acrylate or methacrylate and (c) an ester of the formula ##STR2## where R and R.sub.2 are H or methyl


x is 5 to 80


y is 0 to 20, and


R.sub.1 is alkyl or alkylphenyl.


The reference to bipolymers in this reference are scanty being an afterthought not directed to the invention claimed by Chang et al., namely terpolymers.


The superior performance of the copolymers of the subject application compared with terpolymers of the type taught by Chang et al. is illustrated in the following table, which shows that the presence of the methacrylate, MMA) as a third monomer,
as taught by Chang et al. has a detrimental effect on the viscosity yield in a standard print paste.


______________________________________ Methacrylic Acid (MMA)/  Viscosity of 0.40%  Methyl Methacrylate (MMA)/  Polymer in Standard Print  TERGITOL 15-S-40 Methacrylate  Paste  ______________________________________ (centipoise at room 
temperature)  97.3/ 0/2.7 19,000  87.3/10/2.7 12,500  77.3/20/2.7 10,000  67.3/30/2.7 8,000  57.3/40/2.7 7,000  95.5/ 0/4.5 13,000  55.5/40/4.5 10,000  ______________________________________


These results clearly show a substantial advantage of the MAA/15-S-40 methacrylate copolymer system as taught by the applicants, which is not expected from the teachings of Chang et al.


Although the invention has been described in its preferred form with a certain degree of particularity, it is understood that the present disclosure has been made only by way of example and that numerous changes can be made without departing from
the spirit and scope of the invention.


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Description: This invention pertains to the preparation of copolymers of acrylic acid and nonionic surfactant acrylates and more particularly to their use as thickening agents for aqueous solutions and water/liquid hydrocarbon emulsions.Various synthetic thickening agents composed of carboxylic acid monomers, such as acrylic acid, and a polyfunctional crosslinking monomer are known in the art. These interpolymers produce viscous, aqueous mucilages. However, these interpolymersrely upon the crosslinking monomer to achieve the desired aqueous thickening properties. U.S. Pat. Nos. 2,798,053, 2,858,281, and 3,426,004 disclose respectively polyallyl sucrose, polybutadiene and triallyl phosphate or phosphite esters ascrosslinking monomers for polyacrylic acid to achieve interpolymers capable of producing viscous aqueous mucilages upon neutralization. U.S. Pat. No. 2,798,053 describes crosslinked copolymers of acrylic or methacrylic acid with minor amounts ofvinyl, allyl and methallyl ethers of polyhydric alcohols having at least 4 carbon atoms and at least 3 alcoholic hydroxy groups, wherein the preferred polyalkenyl polyether monomers are polyallyl sucrose and polyallyl pentaerythritol containing anaverage of at least about 3 allyl groups per polyhydric alcohol. Similarly U.S. Pat. No. 3,426,004 describes crosslinked interpolymers of acrylic or methacrylic acids with from 0.1 to 2 weight percent of a polyallyl phosphate or a polyallyl phosphiteester such that at least 2 allyl ester functionalities and preferably 3 allyl ester functionalities are incorporated into the phosphate or phosphite monomer. U.S. Pat. No. 2,858,281 discloses the use of a polymeric crosslinking agent, polybutadiene,in forming the acrylic acid interpolymers.U.S. Pat. No. 3,530,102 issued to Union Carbide Corporation describes terpolymers of maleic anhydride, vinyl alkyl ether and divinylbenzene as thickening agents.U.S. Ser. No. 494,447 discloses ethylene-maleic anhydride interpolymers crossli